Thompson
precision feed mechanism



E. A. THOMPSON Re. 25,720 PREQISION FEED MECHANISM. Original Filed April 18. 1960 I I Jan. '26, '1965 10 Sheets-Sheet 1 INVENTOR. EA RL A THOMPSON xm ATTORNEY 10 Sheets-Sheet 2 M s N m mm cm H F D T N A m E l|||'I m E o m 1 a 1 v l i r J m m 1. H 9 P. 6 w 2 .m m QNN J, 0

mum/ on EARL A. THOMPSON ATTORNEY Jan. 26, 1965 THOMPSON Re. 25,720

PRECISION FEED MECHANISM Original Filed April 18. 1960 7 1o Sheets-Sheet s JNVENTOR. BYEARL '14. THOMPSON A TTORN E Y Jan. 26, 1965 E. A. THOMPSON PRECISION FEED uzcmmxsu 1O Sheets-Sheet 4 Original Filed April 18. 1960 4 9 2 y w 6 a 4. 1 M 8 6 6 W4 6 mmvrox. EA/PL A. THOMPSON A TTOR-N E Y Jan. 26, 1965 I E, A THOMPSON Re. 25,720

PRECISION FEED MECHANISM Original Filed April 18. 1960 10 sheets-sneak IN VEN TOR.

EARL THOMP N BY 9 k fi ATTORNEY Jap. 26, '1965 A. THOMPSON Re'. 25,720

' PRECISION FEED MECHANISM Or inal-Filed Apri1 18 1960 1o Shaqts-Sheet e 0 ii Q A TTOR/VE' Y Jan. 26, 1965 Original Filed April 18. 1960 E. A. THOMPSON PRECISION v FEED MECHANISM 10 Sheets-Sheet 7 I N VEN TOR.

EARL A, THOMPSON ATTORNEY Jan. 26, 1965 E A THOMPSON Re. 25,720

PRECISION FEED MECHANISM I ori inal Filed April 18. 1960 v 10' Sheets-Sheet s INVENTOR.

BY A ATTORNEY EARL A. mompso/v' Jan. 26, 1965 E. A. THOMPSON 25,720

PRECISION FEED MECHANISM Original Filed April 18. 1960 10 Sheets-Sheet 9 INVENTOR.

gIRLA THOMPSON ATTORNEY E. A. THOMPSON PRECISION FEED MECHANISM Original Filed April 18. 1960 Jan. 26, 1965 10 Sheets-Sheet l0 wvw I 3 h wwN Q mm wvw I nmm Nmw n mm EN hm M M mmjm V0 T mm A A 8 MW Y B United States Patent 720 PRECISION FEED MECHANISM Earl A. Thompson, 1300 Hilton Road, Ferndale, Mich. Original No. 3,043,059, dated July 10, 1962, Ser. No. 22,720, Apr. 18, 1960. Application for reissue July 6, 1964, Ser. No. 391,823

23 Claims. (Cl. 51103) Matter enclosed in heavy brackets appears in the original patent but forms no part of this reissue specification; matter printed in italics indicates the additions made by reissue.

This invention relates to machine tools such as grinders. More particularly it relates to precision workpiece feeding mechanism on a multi-purpose base assembly for industrial grinders and to anti-friction ways for overcoming stick-slip motion of a feeding carrier.

The commonly employed dovetail or parallel contact surface ways which guide sliding movement of heavy members on machine tools inherently have a large amount of frictional resistance which must be overcome by the power apparatus which causes the movement. The problem is severe when it is necessary to produce very small movements accurately Consequently, in spite of careful lubrication, the sliding member sticks until initial resistance is overcome, and then slips forward relatively freely for a short distance, and then experiences varying amounts of sticking and resultant slipping during its travel; this obviously renders precise control very difficult to attain.

Attempts to overcome this problem, which prevents accurate sizing of mass produced workpieces, have resulted in air, oil, roller and ball types of anti-friction means employed in place of ordinary guide ways. However, these methods, while overcoming frictional resistance to some extent, are extremely difiicult to engineer and lack the desired ability to accurately guide the heavy moving member and keep it precisely aligned in a desired direction of travel. Misalignment during travel also results in inaccurate sizing which is manifestly undesirable in high precision manufacture.

Accordingly, it is an object of the present invention to provide an improved feed mechanism for a machine tool embodying guide means that have very low frictional resistance and extreme dimensional stability to accurately steer or guide a moving member smoothly along a desired path.

Another object of this invention is to provide a plurality of support members, each having to-and-fro movement relative to the others, all of the relative movements being in the same direction of translation, whereby all of the movements except one provide adjustments for all the changing conditions found in various grinding operations, and the remaining movement is utilized exclusively for feeding successive workpieces to the grinding wheel during the actual grinding operation only.

A further object is to provide a base or bed supporting a grinding wheel as well as a first slide and a feeding carrier usable together as a single multi-purpose base assembly which can be converted to perform a number of distinct types of grinding or other operations merely by the installation of the appropriate workpiece supporting arrangements on the feeding carrier.

A further object is to provide means for guiding movement of a machine tool member, which employs pivoted links and in which anti-friction bearings at the pivot points represent the only points of contact where any frictional resistance could arise.

A still further object is to provide pivoted link guide means wherein twin links constituting a pair of parallel links are interconnected in a manner which resists tor- Reissued Jan. 26, 1965 "ice sional forces to the extent that precise parallelism i: constantly maintained between the two links of a pair.

Yet another object is to provide workpiece feeding ap paratus utilizing two-speed feeding movement of succes sive workpieces comprising a rotating nut and travelling lead screw in a unique arrangement wherein the sam threads along the lead screw are engaged repeatedly a the end of each feeding movement, whereby irregularitie in the threads are minimal in causing variations in th final size of a finished workpiece.

Further objects and advantages of the present inven tion will be apparent from the following detailed descrip tion, with reference to the accompanying drawings it which like reference characters refer to the same part throughout the several views, and in which:

FIGURE 1 is a perspective view of an in-feed center less grinding machine utilizing features of this invention FIGURE 2 is an elevational view of the grinding ma chine utilizing features of this invention with parts brokel away to show the parallel guide links;

FIGURE 3 is a plan view of the machine, partly i1 section; 1

FIGURE 4 is a sectional view taken along line 4 of FIGURE 2 showing the ratchet feed mechanism;

FIGURE 5 is a sectional view taken along line 5-4 of FIGURE 4 also showing the ratchet feed mechanism FIGURE 6 is a sectional view taken along line 6t of FIGURE 2 showing the torsion bar element for main taining the guide links in parallel relationship;

FIGURE 7 is a sectional view taken along line 77 0: FIGURE 9 showing the two speed feed means for the work feed carrier;

FIGURE 8 is a detailed fragmentary sectional viev taken along line 88 of FIGURE 7;

FIGURE 9 is a sectional viaw taken along line 9--S of FIGURE 2 showing the motor for driving the rapit portion of the feed mechanism;

FIGURE 10 is a sectional view taken along line 10-11 of FIGURE 9 showing the motor for driving the slov portion of the feed mechanism;

FIGURE 11 is a view showing a different applicatior of the basic invention;

FIGURE 12 is a view taken along line 12--12 of FIG URE 11;

FIGURE 13 is a view showing still another applicatior of the basic invention;

FIGURE 14 is a view taken along line 14--14 of FIG- URE 13; and

FIGURE 15 is a view in schematic fashion of tilt mechanico-hydraulic power and control unit utilized by this invention.

Referring to FIGURES l, 2 and 3, there is shown 2 grinding machine mounted on the basic convertible as sembly which comprises a base or bed 10, and a suppor or carrier 12 fixed on the base 10 carrying a tool such as 2 grinding wheel 14 which can be reciprocated axially b3 ordinary means schematically shown at 16, and driven by a motor schematically shown at 18. A workpiece holdel or rest 20 positioned adjacent the grinding wheel may have workpieces successively fed to it by any suitable automatic loading means positioned at a location sucl as 22. On the opposite side of workpiece rest 20 frorr the grinding wheel, a regulating wheel 24 serves to hold a workpiece on the rest 20 and slowly rotate it as it is being urged against the grinding wheel during a grinding operation. A coolant tank 17 may be located adjacent the machine. Dressing mechanism for the regulating 'wheel is schematically indicated at 26, and dressing mechanism for the grinding wheel is schematically indicated at 28, both being supported by pivotally mounted compound slide rests. The dresser for the grinding wheel 3 y be fed toward the wheel incrementally prior to each ssing operation by completely automatic means which 1 be explained later.

F adjust the machine to compensate-for dressing the uding wheel, or for a particular variety of workpiece t is to be ground by the wheel, or to move the workt away from the wheel for various infrequent operans such as changing grinding wheels, the workrest 2'9 novable in relation to the grinding wheel by means of a- .t support or base slide 30 mountedon an element of the ;e or bed namely waysdZ and slideable thereon .ong ways 32]. The base slide 30 has a depending hous- :34 through which a lead screw 36 extends. A convennal nut 35 with worm wheel teeth on its periphery is atably mounted in housing 34 threaded on the lead ew 36, and is adapted to be rotated by a Worm gear 35 a conveniently angled shaft 38 which is turned by a nk 40 in the usual manner. The lead screw 36 extends :1 into a housing 42 upstanding on the base it Thus, ation of the cnank 40 serves to move the base slide 3% lard or from the grinding wheel along ways 32 in rela- 1 to the base 10. Consequently, the distance of the rkrest 20 from the peripheral surface of the wheel can regulated by the hand cnank 40.

Each time the grinding wheel 14 is retrued by the :ssing mechanism 28, the workrest 20 must be moved .ially closer to the grinding wheel to compensate for terial removed from the wheel by the dressing opera- 3. Within the housing 42 on the base 10 there is proed automatic means for moving the base slide 30 and lsequently the workrest 20 toward the grinding wheel. Eerring to FIGURES 2, 4 and 5, the automatic advancmeans which constitutes part of the multipurpose base embly is shown in detail. \Vithin the housing 42, the d screw 36 has a worm wheel 43 keyed at 44 thereon. a-rm gear 46 engages the worm wheel 43 and is rotatable means of a shaft 48 journalled at 50 in the housing, 1 having toward one end a wedge taper portion 52, 1 beyond that :a narrower portion whichtermin ates in apped end 54. Surrounding then-arrow end 54 of the tft 48 is a hollow ratchet shaft 56 which also contains lOllOW taper portion matching the portion 52 on the ft 48. A ratchet feed box 57, later to be described, rounds the shaft 56. A hand crank 58 secured by a t 60 to the end 54 of shaft 48 forces the ratchet shaft securely against the wedge taper portion 52 and renders shaft 43, the ratchet shaft 56., and the hand crank 53 nitary structure by which the worm gear 46 may manur be rotated. Thus either hand crank 49 or 58 may used to move the base slide 30 along ways 32, and the nk structure that is not being used will, through its selfking worm gear-worm wheel connection, remain staiary so that the hand crank that is being used will be :otive to move the base slide 30 in relation to the base Norm gear shaft 48 extends in housing 42 beyond worm gear 46 and has secured to its other end a ss gear 47 meshing with another cross gear 49 keyed 51 to a shaft 53 which runs the length of the machine, FIGURES 2, 4, and 11 through 14. Shaft 53 opers at the other end of the machine a chain 55 or similar a pawl 70 and its actuating spring 72 are attached, respectively, and a third radially extending car 74 including segmental gear teeth 76 which mesh with rack teeth '78 on a piston, to be described. Pawl 79 engages the teeth 80 of an annular ratchet 82 formed integral with the ratchet shaft 56. As the oscillating member 62 oscillates clockwise (FIGURE 5), the point of the pawl 7t} engages the teeth 80 of the rotary hatchet $2 and rotates the worm gear shaft 48, thus rotating the lead screw 36 and longitudinal shaft 53.

Oscillating member 62 is rotated clockwise once prior to each dressing operation by reciprocation of a piston 34, having the described teeth '78, which reciprocates in meeting mechanism associated with the grinding wheel :ssing apparatus 28 by means of a one-way ratchet (1 box 57' similar to that associated with the hand nk 58. Thus, as the base slide 3th is moved by rotation worm wheel shaft 48 toward the grinding wheel, the :ssing apparatus 28 is also automatically advanced tord the wheel by the same controlled amount.

Feed box 57 serves to automatically rotate the worm 1r. shaft 48 to advance support 30 on its ways 32 and t ance the dressing apparatus 28, this automatic mecham being designed to be actuated prior to each dressing enation. An oscillating member 62 journaled by means annular bronze bearing sleeve 64 around the ratchet tit 56 has two radially extending ears 66, 68 to which two aligned cylinder sections 86. Connections 88, i l) serve to admit oil against either end of piston 84 thus making it a double acting hydraulic motor. As oil is admitted through the connection 83 at the left-hand end of cylinder 86, piston 84 moves to the right (FIGURE 5) and oscillates the member 62 clockwise. This serves to rotate lead screw 36 and longitudinal shaft 53 to advance both the base slide 30 and the dressing apparatus 28 toward the grinding wheel. As oil is admitted through the other connection 90 on the right-hand end of cylinder 86, piston 84 reciprocates back to the left and turns the oscillating member 62 counter-clockwise but in this directicn the pawl 75) rides over the inclined face of the teeth 8%) of ratchet 82 and does not rotates the shaft 48, as is well known. The length of the stroke of piston 84 and thus the amount of oscillation of member 62 and consequent amount of rotation of lead screw 36 and shaft 53 is closely controlled by an adjustable limit stop 92 in the right-hand end of the cylinder 86.

Means is also provided for rendering the worm gear shaft 4-8 rotatable manually in either direction against the braking action of the pawl and ratchet by means of the hand crank 58 when the fluid motor is at rest. Pawl '79 has a face 92 designed to abut a fixed pin 94 as the piston 84 returns to its rest position against a stop 96 at the left-hand end of cylinder 86. As piston 84 moves to the right by admission of oil through the connection 88, face 92 of pawl 70 moves away from fixed pin 94 allowing the pawl spring 72 to urge the pawl into on gagement with the ratchet teeth and, as the piston $4 returns to its rest position against stop Q6, the last bit of oscillation of member 62 again urges face 92 of pawl 7 6 against the pin 94 and swings the point of the pawl out of engagement with the ratchet teeth. This al lows worm gear shaft 48 to be rotated in either direction by means of the hand crank 58. In the position shown in FIGURE 5, piston 84 has just moved away from the adjustable stop 96 and the pawl is just moving away from the fixed pin 94 and into engagement with the ratchet teeth 80.

Lead screw 36 is thus used to incrementally advance base support or slide 3% prior to each dressing operation and also, by means of hand crank 49, to position base slide 30 and consequently workrest 26 for various size workpieces, changing grinding wheels, or other infrequent operations. Generally, lead screw 36 would also be used to move the workrest 20 toward and away from the face of the grinding wheel with each workpiece as it is successively presented for grinding; however, it will be appreciated that, as the wheel grows smaller from many dressing operations, workrest 2% will be fed into the face of the wheel by different portions of the lead screw; any error encountered in the threads along the length of the lead screw will result in variations in the final size of the workpieces. This invention overcomes this difficulty by providing as part of the basic convertible assembly a second carrier 1% above the base slide 39,

the exclusive function of which is moving or feeding the workpiece toward and from the face of the wheel on successive grinding operations. The carrier 1th? is mounted for motion on the base slide 30 by means of novel anti-friction ways which effectively overcome any the wheel during the actual grinding operation.

stick-slip frictional problems and also precisely guide the movement of the carrier 100 in the direction intended without any misalignment.

Carrier 100 has four bearing blocks 102 thereon, two on each side (FIGURES 1-3 and 6); base slide 30 also has four similar bearing blocks 104 securely mounted thereon, one beneath each of the bearing blocks 102 of the carrier 100. The bearing blocks 104 collectively form an element on the slide 100 for carrying or supporting the carrier 100. Carrier 100 and base slide 30 have cutout portions 106, 108 respectively, on their adjacent faces intermediate the locations where bearing blocks 102 and 104 are secured. These cutouts are provided to allow room for two torsion bar parallel link members 110.

The bars 110 have the upper portions 112 of each side journalled in the opposite bearing blocks 102 on the carrier 100, and the lower portions 114 of each side journalled in the opposite bearing blocks 104 on the base slide 30. Each side of each bar 110, where it is journalled at 112 and 114, is in effect a pivotal linkage between carrier 100 and base slide 30, the four sides of the two bars forming a double parallel linkage system between the carrier and the base slide, and each bar itself serving to interconnect the two fore linkages and the two aft linkages, respectively. While a bar of any shape may be used, the preferred embodiment utilizes a bar having enlarged sides and an interconnecting portion 116 which is generally round in cross section. The entire bar 110 is made of material having qualities of resistance to torsional forces such that the round interconnecting section 116 insures precise parallelism between the upper and lower pivots 112, 114 on each of.

its sides under normal working loads. Thus, as the carrier 100 is moved generally horizontally through a very short circular are about pivot points 114, any tendency for the carrier to wobble or sway out of alignment with its direction of travel will immediately be overcome by torsion member 116, and the carrier 100 will have smooth, precise, almost friction-free motion for its short (usually measured in fractions of an inch) length of travel.

On an in-feed grinding machine, the workpiece rests between the workrest 20 and the regulating wheel 24, and these two members are moved back away from the face of the grinding Wheel (maintaining their same interrelationship) while the finished workpiece is ejected from the rest 20 and a new workpiece is fed onto the rest.

Then, usually by means of a lead screw, the workrest and regulating wheel are moved again toward the face of the grinding wheel until the workpiece contacts the wheel and is treated thereby. The same rate of movement is ordinarily used for bringing the workpiece up to the wheel as well as for pushing the workpiece against However, by use of the carrier 100, this invention may utilize a two-speed feed mechanism which cuts the time in which the workpiece is brought into position against the wheel to a bare minimum. First, the workpiece on its workrest 20 and against regulating wheel 24 is moved rapidly toward the face of the grinding wheel (for instance, for ten thousandths of an inch) until contact is almost made between the workpiece and the grinding wheel; then, a slow, closely controlled rate of speed as the work is being treated (for instance, for one thousandth of an inch) may be provided. Consequently, a great deal of time is saved, comparatively, by making the long approach feed very rapid while the shorter treating feed is necessarily at a controlled, slower rate.

The means for feeding first at a rapid and then at a slower rate which also comprises a feature of the convertible basic assembly is shown in FIGURES 7 through 10, inclusive. Viewing FIGURE 7, the link supported carrier 100 and the base slide 30 in relation to which it moves are fragmentally shown. Threaded at 118 into the end of the carrier 100 is a shaft 120 made of flexible steel and terminating in a piston 122 reciprocable in a 6 r cylinder 124 formed in a housing 126 attached to the base slide 30. Oil under pressure admitted through a connection 128 continually urgesthe piston 122 toward the right-hand end of the cylinder 124 and consequently biases the carrier away from the grinding wheel.

The motion away from the wheel is limited by the smooth face 128 of a block 130, which is also secured to the carrier 100 by means of the screw threads 118, abutting the end of a hollow shaft 132 journalled in sleeve bearings 134 in the housing 136. Hollow shaft 132 has an enlarged annular portion 138 (FIGURE 8) which includes at least one tapered groove 140 into which a similarly tapered key 142 is urged by a spring 144, thus securing shaft 132 against rotary motion, but allowing it to have reciprocatory motion. As the'ishaft 132 moves to the left in FIGURE 7, it pushes against the smooth face 128 of the block 130 on carrier 100, and carrier 100 swings toward the grinding wheel about pivot points 114 on the base slide 30. Since the motion of carrier 100 is arcuate and not precisely rectilinear, a very small amount of up and down motion will accompany the limited forward motion. This is absorbed by the yieldable shaft 120, which will flex upwardly as carrier 100 moves upwardly with its smooth face 128 sliding on the end of the nonflexing hollow shaft 132.

Hollow shaft 132 is in effect a travelling lead screw with threads 146 thereon which mate with the threads of a rotating nut 148 journalled in rugged bearings 150 in housing 136. Around the periphery of nut 148 are gear teeth 152 engaged by opposed racks for turning the nut. As nut 148 is rotated, hollow shaft 132 will move carrier 100. The racks are part of a double headed fluid motor 154 which comprises an upper cylinder 156 and a lower cylinder 158, each having a piston 160 reciprocable therein. Each piston has rack teeth thereon which engage on opposite sides with the teeth 152 around the periphery of nut 146. Oil for moving the upper piston 160 to the left (and lower piston 160 to the right) is admitted to cylinder 156 through a connection 162, and oil for rotating the nut in the other direction is admitted through a connection 164 to lower cylinder 158 to move lower piston 160 to the left (and upper piston 160 back to the right). Motor 154 is for affecting the aforementioned rapid advance of the workpiece toward the face of the grinding wheel.

The length of this rapid advance is regulated by an adjustable stop 166, against which the upper piston 160 abuts at the end of its stroke, mounted in a hollow guide shaft 168 in relation to which it is adjustable by means of a screwthread connection 170. Hollow guide shaft 168 is supported in an extension 172 of the housing 136 by means of bearings 174 and another screw thread connection 176.

For effecting the slow feed which follows the rapid advance, guide shaft 168 has gear teeth 178 peripherally mounted therearound which mesh on either side with racl teeth on pistons 180, 182 of a second double headed hydraulic motor 184 in the housing extension 172, see FIG- URE 10. Oil for actuating the motor 184 by moving piston 182 downwardly within its cylinder 183 is supplied through a connection 185, and oil for returning the pistor in the opposite direction in its cylinder 187 is supplier through a connection 186.

As piston 160 of motor 154 is shot rapidly to the left b3 admission of oil through port 162, nut 148 is rotated anr serves to advance the hollow shaft 132 and thus mow the carrier 100 toward the face of the grinding wheel when piston 160 contacts the adjustable limit stop 166 the rapid feed comes to a stop. At this time, oil is ad mitted through the connection which moves pistol 182 of the second hydraulic motor 184 downwardly an rotates hollow guide shaft 168 which, by means of screv connection 176 in housing 172, causes the shaft 168 am its associated :limited stop 166 to be drawn slowly to th left as viewed in FIGURE 9. Consequently, as the limi :op 166 backs off to the left at a controlled speed and )r a controlled distance, oil in cylinder 156 continues to rge the piston 160 against the limit stop 166, and the :eth on piston 160 continue to rotate the nut 143 very owly and advance carrier 100 (by means of hollow lead :rew shaft 132) in an accurately controlled manner. The nal advance of the workpiece toward the grinding wheel, uring which the grinding operation is completed, finds ie movable parts 146, 148 of the lead screw feeding conection always interrelated in the same position, with the tme threads on rotating nut 148 coacting with the same treads 146 on hollow lead screw shaft 132, thus eliminatig any lead screw error in the final portion of each suc- :ssive feeding movement.

The mechanico-hydraulic or cam-actuated liquid colnn type motion transfer unit for powering and control- 1g the various fluidmotors is schematically shown in [GURE 15. The drive unit 244 includes a motor 246 hich is arranged to drive a self-controlled two-speed ansmission which is shown in the left-hand half of the gure. The motor drives the input shaft 248 of the transission through a belt drive 250. The input shaft 248 ives a pinion 252 and also the input member of a hy- 'aulically engaged, spring released clutch 254. Pinion l2 drives a gear 256 secured to a countershaft 258 which rries pinion 260 at its opposite end. Pinion 269 drives gear 262 and therewith constitutes a set of speed change ars. Gear 262 drives the input member of a second hydrau- :ally engaged, spring released clutch 264. The driven embers of the clutches 254 and 264- are secured to the posite end of a shaft 266 having a worm 268 thereon d a brake drum 270. The latter has a spring biased byaulic motor 272 for engaging the brake. The worm 8 drives a worm wheel 274 secured to the main cam aft 275. For the purpose of automatically controlling the startstopping and speed of the transmission, there is proled a hydraulic control pump 276 driven from gear 262 llCh may circulate a body of oil contained in the transssion housing for control and lubricating purposes. .e pump 276 may deliver to a combined accumulator d relief valve comprising a spring loaded piston 278, d may also supply oil to a bank of control valves 280, 2 and 284. In the diagram, each valve is shown as a o-positioned valve spring biased to the position illusted in which the connections shown in the cross-hatched :tangles are established. Single-headed arrows are used indicate flow at reservoir pressure, and double-headed 'ows to indicate flow at pump delivery pressure. Each the valves, when shifted, establishes the connections )Wii in the unhatched rectangles immediately below the Eched rectangles. Valve 280 is arranged to be shifted by solenoid 286. lves 2 82 and 284 are arranged to be shifted by the ustable cams 288 and 290, respectively, which are posined on camshaft 275. In addition, valve 282 has a iraulic holding cylinder 292 which holds the valve 1 in its shifted position until it is released by the shiftof' valve 284. Valve 280 in the position shown de- :rs pressure fluid to engage the brake 27-2 and supplies ssu're fluid to engage the low speed clutch 264, subject, vever, to a conjoint control at valve 282. [he latter valve, in the position illustrated, exhausts d to release the high speed clutch 254 and places the 1 speed clutch 264 under the control of valve 280. In shifted position, valve 282, provided valve 280 has vn shifted, delivers pressure fluid to engage high speed tch 254 and exhausts fluid to release low speed clutch L. As previously explained, the valve 284 is merely eset valve for by-passing the holding cylinder 292 to mit valve 282 to return to its spring biased position wn on the drawing. .hus, energization of solenoid 286 will start the camft rotating at slow speed; thereafter, the cam 283 will shift the transmission to drive the camshaft at high speed; and, still later, the earn 290 will again shift the trans mission to low speed. So long as the solenoid 286 remains energized, camshaft 275 will continue to rotate, first at a slow speed and then at a high speed during each revolution, controlling its own speed changes by operation of cams 288 and 290.

For the purpose of controlling the drive motor 245 and the solenoid 286, there is provided an electric control circuit connected between a pair of electric supply lines designated L and L The circuit may include a master relay 294 of the holding type having a manual master start switch 296 and a manual master stop switch 293. Relay 2% controls the motor 246 and also a cycle control relay 369 of the holding type, having a manual cycle start switch 3&2 and a manual cycle stop switch 3 M. The normally open contacts of relay 300, which are of the make-before-break type, control energization of cycle solenoid 286 directly. The normally closed contacts of relay 380 also control solenoid 236, but are in series with cam switch 396 mounted on the left end of the master camshaft 275 and arranged to be opened once during each revolution thereof. The arrangement is such that when the cycle stop switch 3&4 is operated at any point in the rotationof camshaft 275, relay 360 will be deenergized but solenoid 236 will remain energized until the cam switch 306 opens at the predetermined stopping point. Operation of the master stop switch 293, however, will de-energize solenoid 2&6 immediately regardless of the point in the cycle and will also de-energize motor 246.

The master camshaft 275 drives a number of cam oper ated hydraulic pulsator sections designated a through g, inclusive. Each section may comprise a cam 36% secured to the camshaft 275 and having a contour composed of predetermined rise and fall ramps designed to produce the motion sequences desired for one of the movable parts of the machine. Each section may comprise a single-acting. pulsator cylinder 316 having a piston 312 operated by the follower for the cam 308. The head of each cylinder 310 may contain a balancing valve assem bly 314 comprising an outwardly opening pressure relief valve and an inwardly opening replenishing valve, each of which is connected to a reservoir 316 which is preferably pressurized at low, superatmospheric pressure.

Each pulsator cylinder 310 communicates by a closed liquid column conduit 318 with one of the hydraulic motors of the machine and thus they together constitute a liquid column type motion transfer system for transmitting the motion of the cam follower to the machine element which is connected to the piston of the fluid motor. Thus, the liquid column 318 of the section b is connected to the head end of a fluid motor 32% for oscillating the grinding wheel 14. Section d is connected to the cylinder 156 of motor 154 for rapidly advancing carrier 1%. Section f is connected to motor 184; for slowly controlling the feed motion of carrier 14%). Sections a, c, e and g are used for various other automatic fluid motor actuated devices related to grinding machine operation, such as loading mechanism for automatically feeding workpieces sequentially to their work position prior to the grinding operation and removing them when the operation is finished.

Each of the fluid motors operates between limit stops which are so arranged that the total displacement of each fluid motor is slightly less than the displacement of the piston 312 in cylinder 31!), thus at the end of each advancing stroke a small quantity of fluid is blown over the relief valve to the reservoir 316. During the latter part of each return stroke the replenishing valve permits the fluid to be returned as well as any small amount that may have leaked out of the liquid column.

For the purpose of returning each of the fluid motors and'their respective transmitter pistons 312, the opposite end of each fluid motor is connected with a plenary volume source of fluid under high pressure which is indicated diagrammatically by the circle RO. It is preferred to utilize a gas loaded liquid accumulator as the high pressure source, although it will be understood that other sources such as spring or weight loaded accumulators, variable displacement pumps with pressure compensation, or fixed displacement pumps with relief valve means may be utilized. Oil under pressure from source R is also utilized to bias the piston 122 in its cylinder 124 in the manner of a hydraulic spring for holding smooth face 128 of block 130 on feed carrier 100 back against the abutting end of the hollow shaft 132 on the base slide 30.

The rapid portion of each rotation of camshaft 275 is utilized for, the non-work performing functions of the grinding machine cycle which desirably should be accomplished as rapidly as possible. The slower portion of the rotation of camshaft 275 is utilized when work is being performed by the grinding wheel on the workpiece, and a more precise control is desired. Thus a more gradual rise on a cam may be employed during the faster portion of the camshaft rotation to give more definite and positive control of non-work performing functions than would the steep rise on a constant speed cam. Consequently, the loading and unloading of successive workpieces and the rapid advance of the workpiece toward the face of the grinding wheel are accomplished in a minimum amount of time, and then the workpiece is urged against the grinding wheel for the exact time desired and at a precisely controlled rate; Immediately upon completion of operation on the workpiece by the grinding wheel, the rapid portion of the camshaft revolution comes into play: the workrest which supports the finished workpiece is rapidly moved away from the face of the grinding wheel; the finishing workpiece is replaced by a new workpiece; and the workrest moves the new workpiece rapidly to a location immediately adjacent the grinding wheel. Then, the slow portion of the camshaft rotation comes into play and the new workpiece is urged against the face of the grinding wheel for a controlled amount of time in completion of a cycle.

Thus a liquid column type motion transfer power and control unit is provided which, merely by the replacement of cams, can be adapted to power and control an unlimited variety of programmed motions in any grinding or other machine tool operation. This drive unit combined with the novel torsion bar interconnected parallel link carrier, for accurate two-speed feeding of a workpiece to a tool such as a grinding wheel may be incorporated with various types of operations.

The entire structure so far described thus constitutes a convertible base assembly upon which structural elements for supporting different types of workpieces for many different grinding operations can be mounted. One type of equipment which can readily be installed upon the feeding carrier 100 of this mechanico-hydraulically powered and controlled base assembly is the equipment illustrated on the base assembly in FIGURES l, 2 and 3. This equipment provides for in-feed centerless type grinding operations.

In order to accomplish bevelling, shouldering or other grinding operations on an in-feed grinding machine, it is desirable to provide a swivel plate 200 rotatable about a swivel pin 202. In this case, the swivel plate 200 is mounted on the feeding carrier 100, the swivel point 2&2 preferably being located directly beneath the center of the workrest 20. Means such as a bolt 204 engaging an arcuate slot 205 is utilized to secure the swivel plate in any desired angular location upon the carrier 100. The workrest 20 is also pivotally secured to the swivel plate and may move therewith or be positioned parallel with the working face of the grinding wheel.

Dovetail ways 206 along the upper face of swivel plate 200 mate with ways on a regulating wheel support 210. A lead screw 212 is rotatably mounted in an upstanding extension 214 of the swivel plate 200, and extends into threaded engagement with the regulating wheel support 210. Rotation of the lead screw 212 by means of a worm wheel 216 keyed thereon and a worm gear 218 serve to move the regulating wheel support 210 along ways 206. A motor 220 associated with the regulating wheel for driving it is provided, as are other means such as an abutment 219 engaging a positioning screw 217 on the support 210 for adjusting the tilt of the regulating wheel about an axis A lying in the plane in which the axes of the grinding wheel and the regulating wheel lie at the completion of the feeding movement.

Thus, in operation, the workrest 20 and the regulating wheel 24 which together form a support for. the workpiece W may be located by means of a hand crank 40 and lead screw 36 the proper distance from the surface of the grinding wheel 14 for the workpiece that is to be ground. Prior to each dressing operation of the grinding wheel by the apparatus 28, both the dressing apparatus 28 and the base slide 30 are automatically moved incrementally closer to the grinding wheel by the fluid motor actuated ratchet mechanism in the housing 42. When the regulating wheel 24 is dresseda very infrequent operationand a certain amount of material removed from the periphery thereof, the regulating wheel support 210 can be moved to again position the regulating wheel the proper distance from the workrest 20 by means of the lead screw 212. Neither of these lead screws 36 and 212 are used for the sequential in-feeding of successive workpieces to the face of the grinding wheel, this operation being accomplished exclusively by the carrier as it moves relative to the base slide 30 on parallel links which are interconnected by torsion bars 116 to insure constant parallelism between the links. The work is fed, first rapidly by motor 154 and then slowly, while the work is being treated by the grinding wheel, by motor 184. These motors are powered by the mechanico-hydraulic programmed driving unit. If desired, the angle of the workpiece resting on workrest 20 and against regulating wheel 24 can be changed in relation to the peripheral working face of the grinding wheel by moving the swivel plate 200 about its swivel 202 on the feed carrier 100, and the regulating wheel may be canted about the axis A by screw 217.

However, many types of work performing equipment other than centerless grinding equipment can be located on the multi-purpose base assembly. For instance, in FIGURES 11 and 12, a chucking grinding operation is semi-schematically shown which utilizes the same base assembly with the mechanico-hydraulic powered and controlled two-speed parallel link feeding carrier for feeding the work. The swivel plate 200' movable about pin 202 will support, however, a spindle mounting 410 which adjustably mounts a powered work holding spindle 412 which may hold or grip a workpiece W either by means of an expanding chuck 414, as shown, or by means of an externally gripping collet. Loading mechanism for supplying new workpieces to the spindle is schematically indicated at 416. Thus, simply by replacing the structure above the swivel plate 200, the basic grinding machine base assembly can easily be converted to handle different types of grinding operations.

The convertibility of the basic assembly is further illustrated in FIGURES 13 and 14, where a between centers grinding operation is also achieved by simply replacing the structure above the swivel plate 200", adjustable by means of locking bolts 204 about a swivel pin 202" on the feed carrier 100, and having guide ways 206" which run at right angles to the ways 206 on the previously described swivel plate 200. Slideable on ways 206" is a spindle support 510 which adjustably mounts a work holding center 512 and an axially retractable center 514 mounted on a fluid retracting means 516 for gripping a workpiece W". Loading mechanism may be located at 518 for supplying new workpieces to thecenters.

In all three of the disclosed types of grinding operations, the pivoted link mounted carrier 100 of this invention is used exclusively for feeding successive workpieces to the grinding wheel, preferably with a two-speed motion powered and controlled by a cam actuated liquid column type programming unit. Merely by converting the means for holding the workpiece to the type of operation desired, a 1nultipurpose base assembly with precision feed mechanism is provided.

Both the pivoted link carrier and the two-speed feed mechanism can readily be adapted, separately or in combination, to any machine tool operation in which mass produced workpieces are presented successively to a tool. This invention is obviously not limited to use in various types of grinding operations.

While the single above described embodiment constitutes a preferred mode of carrying out this invention as illustrated in relation to several types of grinders, other forms of the basic invention might readily be adopted within its actual scope; consequently, the invention is variously claimed as:

1. Precision workpiece feed mechanism for a machine tool, comprising: a base; two carriers on the base; a workpiece holder and a tool, one carried by each carrier; means permitting relative movement between the holder and the tool, the means including a first pair of spaced, aligned pivot points on one carrier, a bar having two sides, each side being connected to one of the first points, a second pair of spaced, aligned pivot points on the base parallel with the first pair of points, each side of the bar being also connected to one of the second points, and the bar having qualities of resistance to torsional forces adequate to insure parallelism between the two aligned pairs of pivot points under normal working loads.

2. Precision workpiece feed mechanism for a. machine tool, comprising: a base; two carriers on the base; a workpiece holder and a tool, one carried by each carrier; means permitting relative movement between the holder and the tool, the means comprising two units, each of the units including a first pair of spaced, aligned pivot points on one carrier, a bar having two sides, each side being connected to one of the first points, a second pair of spaced, aligned pivot points on the base parallel with the first pair of points, each side of the bar being also connected to one of the second points, the pairs of aligned pivot points in each of the two units being parallel, and the bar having qualities of resistance to torsional forces adequate to insure parallelism between the two aligned pairs of pivot points under normal working loads.

3. Precision workpiece feed mechanism for a machine tool, comprising: a base; two carriers on the base; a workpiece holder and a tool, one carried by each carrier; means permitting relative movement between the holder and the tool, the means comprising two units, each of the units including a first pair of spaced, aligned pivot points on one carrier, a bar having two sides, each side being connected to one of the first points, a second pair of spaced, aligned pivot points on the base parallel with the first pair of points, each side of the bar being also connected to one of the second points, the pairs of aligned pivot points in each of the two units being parallel and the distance be :ween the two first pairs of pivot points of each unit being equal to the distance between the two second pairs of pivot points of each unit and the bar having qualities of resistance to torsional forces adequate to insure parillelism between the two aligned pairs of pivot points mder normal working loads.

4. Precision workpiece feed mechanism for a machine 001, comprising: a base; two carriers on the base; a workniece holder and a tool, one carried by each carrier; means )errnitting relative movement between the holder and the col, the means including a first pair of spaced, aligned )ivot points on one carrier, :1 bar having two sides, each .ide being connected to one of the first points, a second )air of spaced, aligned pivot points on the base parallel with the first pair of points, each side of the bar being also connected to one of the second points, and the bar having qualities of resistance to torsional forces adequate to insure parallelism between the two aligned pairs of pivot points under normal working loads; means limiting the relative movement when a predetermined minimum distance exists between the holder and the tool; and a lead screw feeding arrangement interconnecting the base and the one carrier for causing the relative movement until the minimum distance exists.

5. Precision workpiece feed mechanism for a machine tool, comprising: a base; two carriers on the base; a workpiece holder and a tool, one carried by each carrier; means permitting relative movement between the holder and the tool, the means including a first pair of spaced, aligned pivot points on one carrier, a bar having two sides, each side being connected to one of the first points, a second pair of spaced aligned pivot points on the base. parallel with the first pair of points, each side of the bar being also connected to one of the second points, and the bar having qualities of resistance to torsional forces adequate to insure parallelism between the two aligned pairs of pivot points under normal working loads; means limiting the relative movement when predetermined minimum and maximum distances'exist between the holder and the tool; and means causing the movement from the minimum to the maximum distance and the first portion of the movement from the maximum to the minimum distance at a speed greater than the remaining portion of the movement from the maximum to the minimum distance.

6. Precision workpiece feed mechanism for a machine tool, comprising: a base; two carriers on the base; a workprice holder and a tool, one carried by each carrier; means permitting relative movement between the holder and the tool, the means including a first pair of spaced, aligned pivot points on one carrier, a bar having two sides, each side being connected to one of the first points, a second pair of spaced, aligned pivot points on the base parallel with the first pair of points, each side of the bar being also connected to one of the second points, and the bar having qualities of resistance to torsional forces adequate to insure parallelism between the two aligned pairs of pivot points under normal working loads; means for causing the relative movement including afluid motor operable between the holder and the tool, a rotary cam actuated pulsator, and a liquid column connecting the pulsator with the motor whereby the relative movement will follow aprogrammed sequence.

7. Precision workpiece feed mechanism for a grinding machine, comprising: a base; two supports on the base; a grinding wheel and a carrier, one on each support; means on the base permitting to-and-fro motion relative thereto of one of the supports in one direction; means associated with the carrier and its support permitting toand-fro motion of the carrier relative to its support in the one direction including pairs of twin links interconnecting the carrier and its support, each link being parallel with its twin, means formed as a unit with both links of a pair and extending therebetween to resist torsional forces and insure parallelism between both links of a pair under normal working loads; a workpiece holder on the carrier; and means for effecting the two motions in the one direction.

8. Precision workpiece feed mechanism for a grinding machine, comprising: a base, two supports on the base; a grinding wheel and a carrier, one on each support; means on the base permitting to-and-fro motion relative thereto of one of the supports in one direction; means associated with the carrier and its support permitting to-and-fro motion of the carrier relative to its support in the one direction'including pairs of twin links interconnecting the carrier and its support, each link being parallel with its twin and the said pairs of twin links also being parallel with each other, means formed as a unit with both links of a pair of extending therebetween to resist torsional forces and insure parallelism between both links of a pair under normal working loads; a workpiece.

holder on the carrier; and means for effecting thetwo motions in the one direction.

9. Precision workpiece feed mechanism for a grinding machine, comprising: a base; two supports on the base; a grinding wheel and a carrier, one on each support; means on the base permitting to-and-fro motion relative thereto of one of the supports in one direction; means associated with the carrier and its support permitting to-and-fro motion of the carrier relative to its support in the one direction including pairs of twin links interconnecting the carrier and its support, each link being parallel with its twin, means formed as a unit with both links of a pair and extending therebetween to resist torsional forces and insure parallelism between both links of a pair under normal working loads; a workpiece holder on the carrier; and means for efiecting the two motions in the one direction, the means for effecting motion of the carrier relative to its support including a lead screw feeding arrangement interconnecting the carrier and its support; and means limiting relative motion between the carrier and its support.

10. A base assembly for grinding machines, comprising: a base; two supports on the base; a grinding wheel and a carrier, one on each support; means on the base permitting to-and-fro motion relative thereto of one of the supports in one direction; means for effecting the motion; pivoted link means interconnecting the carrier and its support permitting to-and-fro motion of the carrier relative to its support also in the one direction; two-speed driving means for effecting the motion of the carrier relative to its support; a rotary cam actuated liquid column type motion transfer device for powering and controlling the driving means; the carrier adapted to detachably mount a variety of workpiece holding equipment whereby a workpiece may be movably supported in relation to the grinding wheel.

11. A machine tool comprising a base, a member to be shifted to and fro relative to the base, and means forming an anti-friction mounting for the member including a first and second parallelogram linkage, one at each side of the member, and a pair of torsionally rigid connectors each joining a link of one parallelogram to a laterally spaced link of the other parallelogram whereby the member may partake of a limited translatory motion in an arcuate path.

12. A machine tool comprising a base, a member to be shifted to and fro relative to the base, and means forming an anti-friction mounting for the member including a first and second parallelogram linkage, one at each side of the member, and a pair of torsionally rigid connectors each joining a link of one parallelogram to a laterally spaced link of the other parallelogram whereby the member may partake of a limited translatory motion in an arcuate path and a set of ways having a slide shiftable thereon and forming a second support between the member and the base for translatory motion through a greater distance.

13. A machine tool comprising a base, a member to be shifted to and fro relative to the base, and means forming at least three compound slide-supports for the -member, at least two of which are subject to sliding friction and at least one of which provides an anti-friction mounting for the member including a first and second parallelogram linkage, one at each side of the member, and a pair of torsionally rigid connectors each joining a link of one parallelogram to a laterally spaced link of the other parallelogram whereby the member may partake of a limited translatory motion in an arcuate path.

14. A machine tool comprising a base, a member to be shifted to and fro relative to the base, and means forming at least three compound slide-supports for the member, at least two of which are subject to sliding friction and at least one of which provides an anti-friction mounting for the member including a first and second parallelogram linkage, one at each side of the member, and a pair of torsionally rigid connectors each joining a link of one parallelogram to a laterally spaced link of the other parallelogram whereby the member may partake of a limited translatory motion in an arcuate path, independent lead screw actuators for each of the slide supports, a stop for terminating the motion of the lead-screw for the anti-friction mounted slide support at a single position along the lead screw, means for acuating the last named lead screw against the. stop, and means for thereafter moving the stop to impart a final feeding motion to the member.

15. A machine tool comprising a base, a member to be shifted to and fro relative to the base, and means forming an anti-friction mounting for the member including a first and second interconnecting link, one at each side of the member, and a torsionally rigid connector joining the links to form therewith an integral supporting structure whereby the member may partake of a limited translatory motion in an arcuate path.

16. Feed mechanism for a grinding machine comprising a base, a grinding wheel mounted for rotation on the base, a wheel dressing mechanism mounted on the base, means connected to cause relative movement between the dressing mechanism and the wheel in small increments to establish the depth of the dressing cut, a workpiece manipulating mechanism mounted on the base for feeding workpieces successively to the wheel, means connected to cause relative movement between the manipulating mechanism and the wheel in correspondingly small increments to compensate for the depth of the dressing cut, and a single rotary cam powered and controlled liquid column type motion transfer device connected to operate both of the movement causing means whereby the two mechanisms partake of identical infeed movements.

17. A machine tool comprising a base supporting a work performing tool, a member to be shifted cyclically to-and-fro on the base relative to the tool, and means forming at least three compound slide-supports for the member, at least two of which are subject to sliding friction and at least one of which provides an anti-friction mounting for the member, feed means connected to the one slide-support to produce small increments of feed motion to-and-from the tool, compensating means connected to the other slide-supports to produce semi-permanent spacial adjustments between the tool and the member, and a workpiece handling mechanism on the member whereby the feed means operating the one anti-friction mounted slide exclusively generate the cyclical infeed motion of the workpiece to the tool.

18. A machine tool comprising a base supporting a Work performing tool, a member to be shifted to-and-fro on the base relative to the tool, workpiece handling means on the member adapted to present workpieces successively to the tool, a two-speed feed means including a shiftable piston type fluid motor operatively connected between the base and the shiftable member and having a pair of limit stops to govern the stroke of the piston, one of the stops terminating rapid feed motion of the member toward the tool, and means for moving the one stop in a stroke increasing direction upon completion of the rapid feed motion to impart a final slower feeding motion to the shiftable member.

19. A machine tool comprising a base supporting a work performing tool, a member to be shifted to-andfro on the base relative to the tool, workpiece handling means on the member adapted to present workpieces successively to the tool, a two-speed feed means including a shiftable piston type fluid motor operatively connected between the base and the shiftable member and having a pair of limit stops to govern the stroke of the piston, one of the stops terminating rapid feed motion of the member toward the tool, and means for moving the one stop in a stroke increasing direction upon completion of the rapid feed motion to impart a final slower feeding motion to the shiftable member, a second fluid motor connected to operate the last-named means, and a rotary cam powered and controlled liquid column type motion transfer device connected to operate the two fluid motors in timed sequence whereby workpieces are presented to the tool with a rapid approach motion followed by a slower feed motion.

20. A machine tool comprising a base member and a shifitaole memlber supported thereon for 'to-and fro motion relative to the base member, a lead screw interconnecting the members to cause the to-and-tro shifting motion, bearing means on one of the members supporting the lead screw for rotary and against axial motion, selflocking means connected with the bearing means normally preventing rotation of the lead screw, manual means for unlocking the self-locking means and selectively rotating the lead screw, a nut on the other member supported for rotary and against axial motion and threadably engaging the lead screw, self-locking means on the other member normally preventing rotation of the nut, and manual means for unlocking the self-locking means and selectively rotating the nut whereby the shiftable member may be moved relative to the base member by manual means located either on the base member or on the shiftable member. 1

21. A machine tool comprising in combination a base carrying a work performing tool and including'an element supporting a member for supporting a workpiece which member is cyclically to be fed toward the tool and removed from the tool, two supports each including an element which is movable to-and-fro in the same direction relative to the base and relative to the tool, a first of said supports being carried by the element of the base, and the second of the supports being carried by the element of the first support and carrying the workpiece supporting member, one o the supports having a stick-slip free connection between such one support and the element which carries such one support, feed means connected to said one support, cyclical means for operating the feed means to move the workpiece supporting member cyclically toward and away from the tool, compensating means connected to the other support for producing semi-permanent space adjustments between the tool and the member, and a workpiece holding mechanism on the member whereby the feed means operating that support having the stick-slip free connection exclusively generates cyclical infeed motion of the workpiece to the tool.

I 22. A machine tool comprising a base including an element for supporting a member, a member to be shifted to-and-fro relative to the base; two supports each including an element which is movable to-and-fro in the same direction relative to the base, a first of said supports being carried by the element of the base and the second of the supports being carried by the element of the first support and carrying the member; and an anti-friction mounting between one of the supports and one of said elements, said mounting being characterized by absence of stick-slip and including a first and a second parallelogram linkage, one at each side of such one support, and including links connecting such one support and said one of said elements; and a pair of torsionally rigid connectors each connecting a link of one parallelogram to the corresponding link of the other parallelogram whereby the member can partake of limited translatory motion in an arcuate path.

23. Apparatus as defined in claim 22 characterized by an independent actuator for each of the supports, a stop for terminating motion of the anti-friction mounted support, means for urging the anti-friction mounted support in the direction to be halted by the stop, and means for thereafter moving the stop to impart a final feeding motion to the member.

7 References Cited by the Examiner The following references, cited by the Examiner, are of record in the patented file of this patent or the original patent.

UNITED STATES PATENTS 1,818,675 8/3 1 Cushman 51-1665 XR 2,720,734 16/ 5 S Heckethorn et al. 2,904,936 9/59 Veith 5 1--103 3,094,816 6/6 3 Dreier 51-92 LESTER M. SWINGLE, Primary Examiner. 

